Group Distribution Normal

[inigoelv]

Good morning;

I need the help with a distribution normal formul:

"Only(Normdist(Round([Gramaje Laboratorio (gr/m2)],0.1), Avg(total [Gramaje Laboratorio (gr/m2)]),Stdev(total [Gramaje Laboratorio (gr/m2)]), 0))*0.1*Count(total [Gramaje Laboratorio (gr/m2)])"

I need to group it by a field call "Descripcion Articulo Compacta", but only the formul let me insert in the last part of the formul the expression <[Descripcion Articulo Compacta]> .

I attached one photo with the effect.

Thanks in advance.